Zoology - Principles of Inheritance and Variation Question with Solution | TestHub

Haemophilia, a hereditary (recessive X-linked) disease is caused due to fault in genes, which controlling the factor VIII and IX, located on X-chromosome. The male carries only one X-chromosome, his other sex chromosome, which carries no genes for blood clotting, so the condition is usually seen only in males where only one faulty chromosome is needed. While a female with one faulty X-chromosome will be carrier. So, in females two faulty X-chromosomes are needed to cause the disease.